I have a CORE with Leupold Deltapoint mounted. A CORE has higher irons. They can be seen through the optic, unlike a MOS, which needs higher sights installed if the optic is not to be the only sighting option.
If the sight picture is shifted around, it is possible to see: only the dot; the irons and the dot; the irons. When the irons and dot are visible at the same time, it can be confirmed that the irons and the optic have the same zero.
I consider the irons to be backup sights, in the event of a failure of the optic. Otherwise, I am not interested in seeing them. The great advantage of the optic is that there is no sight alignment. Dot on target, and squeeze.
Incidentally, zeroing a Deltapoint mounted on a CORE is a pain. No wonder they replaced it with the Pro.